Numerical Study of Atrial Fibrillation Effects on Flow Distribution in Aortic Circulation

Area of Science:

• Cardiovascular Physiology
• Biomedical Engineering
• Computational Fluid Dynamics

Background:

• Atrial fibrillation (AF) is a common arrhythmia impacting cardiac function and potentially leading to stroke.
• The precise mechanisms and origins of thromboembolism in AF patients remain debated.
• Alternative hypotheses suggest thrombus formation in the aorta or carotid arteries.

Purpose of the Study:

• To investigate the impact of common atrial fibrillation (AF) traits on aortic blood flow dynamics.
• To quantify the sensitivity of aortic flow to specific AF-related conditions.
• To explore the potential for atherogenesis and thrombus formation in the aorta due to AF.

Main Methods:

• Coupled in-house codes with ANSYS-CFX for computational fluid dynamics (CFD) simulations.
• Parametric study analyzing four AF traits: lack of atrial kick, atrial remodeling, left ventricle systolic dysfunction, and high-frequency fibrillation.
• Quantification of aortic flow rate and flow structures.

Main Results:

• AF traits significantly reduce flow rate at the left ventricular outflow tract.
• Reduced flow impacts systemic, cerebral, and coronary blood perfusion.
• Increased endothelial cell activation potential (ECAP) and altered flow patterns were observed.
• Predisposed regions for atherogenesis and thrombus formation identified in the ascending aorta, aortic arch, and descending thoracic aorta.

Conclusions:

• Atrial fibrillation significantly alters aortic hemodynamics, reducing overall blood perfusion.
• AF-induced flow changes create conditions conducive to atherogenesis and thrombus formation within the aorta.
• Findings contribute to understanding AF-related stroke risk beyond intra-atrial clot formation.